Antihalation protective layer



April 1944- G. F. NADEAU ETAL ,346,078

ANTIHALATION PROTECTIVE LAYER Filed Nov. 22, 1941 LS/ON.

F/LM SUPPORT.

PERMEABL E ANT/HAL A T/ON L14 YER PROTECTIVE LAYER 0F CELLULOSE ORGAN/CA CID ESTER.

GALE E/YADEAU R/CHARDEMLLER IN VEN TORS BY 4% M ATTORNEYS Patented Apr.4, 1944 1 2,346,078 ANTIHALATION PROTECTIVE mm Gale F. Nadeau andRichard F. Miller, Rochester, N. Y., assignors to Eastman Kodak Company,Rochester, N. Y., a corporation of New Jersey Application November 22,1941, Serial No. 420,088

6 Claims.

This invention relates to photographic antihalation film and moreparticularly to antihalation film carrying a protective layer for theanti halatlon layer.

One problem in connection with coating antihalation backing layers ontophotographic films, is the tendency for the dyes to bleed or diflusefrom the layer into adjacent layers, such as emulsion layers, when filmis wound on a spool or several sheets of film are placed one upon theother. One method for overcoming this difiiculty has been disclosed inthe Nadeau and Slack U. S. Patent No. 2,326,057, granted August 3, 1943,and consists in converting the dye and the carrier material of anantihalation layer to a less water soluble salt through the use ofslightly soluble or insoluble organic amines.

We have discovered a superior method of overcoming this bleedingtendency of antihalation dyes, which consists in overcoating the dyelayer with a protective layer of cellulose organic acid ester permeableto photographic processing solutions. It is not always suflicient tocoat such a layer from solvent solutions chosen at random, for in someinstances with improper solvents, the dye may be carried into the backoi. the film support or may be redistributed into the protective layeritself. In the preferred embodiment of our invention, a solvent ischosen for coating the protective layer which has a minimum attack onthe vehicle of the antihalation layer, and in which the light-absorbingmaterial is not appreciably soluble.

The accompanying drawing shows in cross-sectional view a photographicfilm constructed in the manner of the invention;

In the drawing, a film support l0, which may be a cellulose ester,synthetic resin or similar material, carries a sensitive emulsion layerII, on one side, or a multiplicity of difierently sensitized emulsionswhich may also be colored with dyes bleachable under influence ofsilver, and on the other side an antihalation layer ll, of celluloseorganic acid ester, containing fugitive dyes, permeable to photographicprocessing solutions, and over which is the protective layer l3 of theinvention, which may either be only permeable to, and not soluble in,photographic processing solutions, or it may be both permeable andsoluble in said solutions.

- Our invention is better understood by consideration of the followingexamples which are only illustrative of the numerous modifications andequivalents of which our invention is capable,

and are not intended to limit the scope of the invention.

Example I A photographic film support of cellulose acetate propionate orcellulose nitrate suitably subbed if desired as shown in Examples 1 and4 of Nadeau and Slack U. S. Patent 2,289,799, granted July 14, 1942, maybe coated with a dope of the fol lowing typical composition.

Per cent Cellulose acetate phthalate (27 per cent acetyl, 13 per centphthalyl) 4.5 Acetone 45 Methyl Cellosolve 20 Ethanol 30.5

overcoated with a thin layer of cellulose acetate phthalate of the samecomposition, although it need not be the same, as used in the antihalation layer, usingthe following formula:

Per cent Cellulose acetate phthalate 1.5 Ethyl acetate (13% ethanol)98.5

In the above formula pure ethyl acetate, or the commercial gradeindicated, containing some ethyl alcohol, may be used to the extent thatthe dye layer is not adversely affected. The amount of a dye solvent,such as alcohol, which may be tolerated, is dependent upon the dyedensity in the antihalation layer. Thus when the density is such thatonly antihalation protection is provided, an appreciable amount may betolerated, however, if a greater density of dye is required, as forinstance, to give adequate leader protection for daylight loading'offilm, then the degree of activity of the solvent must be reduced.Generally, about 10-15% of active dye solvent may be tolerated.

. Example II The antihalation layer, of a film of the type described inExample I suitably subbed if desired and coated with cellulose acetatephthalate, may be tinted with a solution containing about parts of ethylalcohol, 10 parts of water and about 1.5 parts of a fugitive dye such asAcid Magenta (800), Acid Green (764), Acid Blue 3R, Luxol BrilliantGreen BL (guanidine salt of Acid Green) or sulfonated Malachite Green.In addition. the dye solution may contain a surface-active agent such asAerosol AY (sodium suli'o diamyl succinate) in the amount of about 1-5per cent. Over the dye layer is applied a 5 per cent solution ofcellulose acetate phthalatein a mixture of 94 parts of ethylene chlorideand 6 parts of alcohol. In a similar manner our invention may be appliedto other suitable photographic fllm supports of materials such assynthetic resins, cellulose esters, as for instance, cellulose acetate,cellulose propionate, etc., celluose mixed organic acid esters, e. g.,cellulose acetate propionate, cellulose acetate butyrate or cellulosenitrate. These supports may carry a suitable antihalation layer of amaterial preferably only permeable to photographic processing solutions,however, antihalation layers soluble in photographic processingsolutions may be used if desired, in which case a light-absorbingmaterial, such as carbon or a non-fugitive dye may be used.

Antihalation layers of the preferred type comprise the cellulose organicacid dicarboxylic acid esters disclosed in Nadeau and Slack U. S. Patent2,311,073, granted February 16, 1943, that is, cellulose esterscontaining substantially 4-8 acyl groups per C14 cellulose unit of whichnot more than one is a dicarboxylic acid acyl group and the remainderare monobasic acid groups. Such esters are permeable to, but not solublein, photographic processing solutions such as a developer. In addition,the cellulose monobasic organic acid esters disclosed in the same patentapplication may be used. Similarly, materials soluble in photographicprocessing solutions, as for instance, the alkali soluble celluloseorganic acid dicarboxylic acid esters disclosed in the Nadeau and SlackU. S. Patent 2,289,799, above cited, may be employed. In applying theantihalation layers to film supports the methods shown in the abovecitedapplications may be used.- Other antihalation layers containing resinvehicles, such as disclosed in the Nadeau and Slack U. S. Patent tainsanother cellulose organic acid dicarboxylic acid ester of difi'erentcomposition, or a partially hydrolyzed cellulose monobasic organic acidester of the composition shown in the application cited immediatelyabove. In this case it is necessary to choose a solvent which willadhesively join the ester of the protective layer to the antihalationlayer and at the same time will not adversely aflect the dyedistribution in the antihalation layer. This is more difiicult than inthe case where the two layers contain the same cellulose ester.

Other cellulose esters useful in the protective layer are alkali solublecellulose organic acid dicarboxylic acid esters such as those disclosedin U. S. Patent 2,289,799 above cited in which case non-fugitive dyes orcarbon may also be used in th antihalation layer. It is, therefore,obvious that from the materials useful in the protective layer of ourinvention may be chosen cellulose esters only permeable to photographicprocessing solutions, or both permeable and soluble in said solutions.

There are numerous variations of our methods which assist in attainmentof the utmost in prevention of dye bleeding and which maybe used inconjunction with the protective layer of the invention. For instance, ifdesired, as disclosed in the Nadeau, Slack, and Smith, U. S. patentapplication, Serial N0. 415,590, filed October 18,

1941,"to the antihalation layer or protective layer coating solutionsmay be added surface-active agents to promote penetration of processingsolutions. Also, as disclosed in the Nadeau and Slack U.- S. Patent2,326,057, varicus amines such as dioctyl amine or toluidine, may beused to form'salts with the dyes and carrier materials to aid in thefixation of the dye in the antihalation layer.

It is to be understood that the disclosure herein is by way of exampleand that we consider as included in our invention all modifications andequivalents falling within the scope of the appended claims.

What we claim is:

l. A light sensitive photographic film comprising a support carrying asilver halide emulsion layer on one side thereof, on the other side an2,319,080, granted May 11, 1943, may be provided so antihalation layerof cellulose organic acid ester with the protective layers of theinvention if suitable solvent solutions are used.

Films provided with antihalation layers in this manner are nowsusceptible to application of the protective layer of the invention.Materials preferred for use in this layer are the cellulose organic aciddicarboxylic acid esters and the cellulose monobasic organic acidesters, such as those disclosed in Patent 2,311,073, above cited, havingsubstantially 4-8 acyl groups per C24 cel lulose unit of which not morethan one is a dicarboxylic acid acyl group and the remainder aremonobasic acid acyl groups. As previously mentioned, one chooses asolvent solution for the cellulose ester which has a minimum of attackon the vehicle of the antihalation layer and in which the antihalationdye, or dyes, is insoluble or not appreciably soluble. Solvents of thetype useful when the antihalation layer and the propermeable to, but notsoluble in, photographic processing solutions, and over the antihalationlayer a protective layer of cellulose organic acid dicarboxylic acidester permeable to photographic processing solutions.

2. A light sensitive photographic film comprising a support carrying asilver halide emulsion layer on one side thereof, on the other side anantihalation layer of cellulose organic acid ester permeable to, but notsoluble in, photographic processing solutions, and over the antihalationlayer a protective layer of cellulose organic acid dicarboxylic acidester permeable to, but not soluble in, photographic processingsolutions and coated from a solvent solution in which the lightabsorbingmaterial of the antihalation layer is not appreciably soluble.

3. A light sensitive photographic film comprising a, support carrying asilver halide emulsion tective layer contains cellulose organic aciddilayer on one side thereof, on the other side an carboxylic acid estersare. shown in the preceding examples.

The method is not quite so simple if the antihalation layer and theprotective layer contain antihalation layer of cellulose organic acidester permeable to, but not soluble in, photographic processingsolutions, and over the antihalation layer a. protective layer ofcellulose organic acid different cellulose esters, e. g., if eitherlayer con- 16 d ar xy acid ester having substantial y 4-8 acyl groupsper C24 cellulose unit of which not more than one is a dicarboxylic acidacyl group and the remainder are monobasic acid acyl groups coated froma solvent solution in which the light-absorbing material of theantihalation layer is not appreciably soluble.

4. A light sensitive photographic film comprising a support carrying asilver halide emulsion layer on one side thereof, on the other side anantihalation layer of a cellulose organic acid dicarboxylic acid esterhaving 4-8 acyl groups per C24 cellulose unit of which not more than oneis a dicarboxylic acid acyl group and the rest are monobasic acid acylgroups, and over the antihalation layer a protective layer of acellulose organic acid dicarboxylic acid ester having 4-8 acyl groupsper C24 cellulose unitof which not more than one is a dicarboxylic acidacyl group and the rest are monobasic acid acyl groups coated from asolvent solution in which the lightabsorbing material oi theantihalation layer is not appreciably soluble.

5. A light sensitive photographic film comprising a support carrying asilver halide emulsion layer on one side thereof, on the other side anantihalation layer of a cellulose organic acid ester permeable to, butnot soluble in, photographic processing solutions, and over theantihalation layer a protective layer of a cellulose organic aciddicarboxylic acid ester soluble in photographic developing solutions. a

6. The method of providing a sensitive antihalation photographic filmwith a protective layer for an antihalation layer of a cellulose organicacid ester permeable to, but not soluble in, photographic processingsolutions, which comprises coating said layer with a layer of celluloseorganic acid dicarboxylic acid ester permeable to, but not soluble in,photographic processing solutions from a solvent solution in which thelightabsorbing material of the antihalation layer is not appreciablysoluble.

GALE F. NADEAU. RICHARD F. MILLER.

